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Date:   Thu, 21 May 2020 19:09:14 -0700
From:   Andi Kleen <>
        Andi Kleen <>
Subject: [PATCH] perf script: Don't force less for non tty output with --xed

From: Andi Kleen <>

--xed currently forces less. When piping the output to other scripts
this can waste a lot of CPU time because less is rather slow.
I've seen it using up a full core on its own in a pipeline.
Only force less when the output is actually a terminal.

Signed-off-by: Andi Kleen <>
 tools/perf/builtin-script.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 56d7bcd12671..c4c6a00e0341 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -3286,7 +3286,10 @@ static int parse_xed(const struct option *opt __maybe_unused,
 		     const char *str __maybe_unused,
 		     int unset __maybe_unused)
-	force_pager("xed -F insn: -A -64 | less");
+	if (isatty(1))
+		force_pager("xed -F insn: -A -64 | less");
+	else
+		force_pager("xed -F insn: -A -64");
 	return 0;

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